Entry doors, patio doors, and the like generally include a pair of spaced vertical side jambs and a door sill extending between the bottom ends of the side jambs to form a portion of a door frame. Hinged or sliding door panels are mounted within the resulting frame and, when closed, directly overly a threshold portion along the inside of the sill. Many hinged entry doors open into a building in which they are mounted and thus are know as in-swing doors. A variety of sill configurations are available for use with entry doors including wooden sills, aluminum sills, plastic sills, composite sills, and the like.
One type of sill used for entry doors is known as a “contain-and-drain” sill. In general, a contain-and-drain sill typically is extruded from plastic, aluminum, or a composite material and is generally hollow inside with, perhaps, some longitudinal support ribs, which form chambers inside the sill. Openings are formed in the support ribs enabling communication of fluids between adjacent chambers. The ends of the sill are sealed with an end cap and one or more weep holes are formed along an outside nosing of the sill and communicate between the hollow interior and the outside environment. The weep holes may be provided with weep doors or flaps. Drains are generally arranged on the threshold of the sill and function as portals for water to flow from the threshold into the hollow interior of the sill. Once within the interior of the sill, water can drain from the sill and through the weep holes to the outside. Additionally, such drains also function as vents helping to equalize pressure differentials that develop at times between the outside of a doorway and the inside of a building and to vent air displaced by rising water in the sill.
Rainstorms are sometimes accompanied by very high winds that can raise the air pressure on the exterior of a doorway relative to the interior of the doorway, creating a partial vacuum within the hollow interior of a contain-and-drain door sill. As used herein, the term “partial vacuum” means that there exists a negative pressure differential between the outside of the doorway and the hollow interior of the door sill. The partial vacuum can cause rain water to be sucked through weep holes along the outside nosing of the sill and into the interior of the sill, causing the sill to fill progressively with water. A relationship exists between the magnitude of the partial vacuum and the height of the column of water, which establishes a head of water pressure within the sill. The water in the sill generally rises until the head of water pressure is balanced by the pressure differential between the outside and inside of the doorway. Often, and particularly in driving rains, there also is collected water on the threshold portion of the sill draining into the interior of the sill. If the winds are extreme enough, causing the partial vacuum to increase sufficiently, the water level within the sill can rise to a level that exceeds the capacity of the sill, forcing the water to escape. The water generally does so through the drains in the threshold and elsewhere and pools on an upper surface of the sill. The pooling water has an increased likelihood of entering the dwelling and causing water damage. Leakage into a dwelling can cause the doorway to fail to meet building standards for water resistance, particularly in hurricane prone regions such as coastal areas.
The DP rating of a door sill is based on laboratory pressure testing and is measured in pounds per square foot, or psf. Generally speaking, the DP rating is a measure that is a function of a height of a column of water the contain-and-drain sill can accommodate under blowing rain conditions before the sill fills and begins to leak. The greater the height of the water column the sill can contain under wind generated pressure, the larger the DP rating. A typical contain-and-drain door sill may have a DP rating of about 35 to 40. Sills with such ratings, while adequate in most regions, can be inadequate in areas such as coastal regions that are prone to tropical storms and hurricanes where rain is accompanied by exceedingly high wind conditions.
A need therefore exists for n doorway with a contain-and-drain sill that effectively contains and allows a greater head of water to be established within the sill under high wind load conditions without leaking and that drains water effectively from the sill under normal rainy conditions. It is to the provision of such a doorway that the present disclosure is primarily directed.